Servo-controlling method of an optical disk apparatus

ABSTRACT

The present invention relates to a servo-controlling method of an optical disk apparatus. In the present invention, an order on which servo-control manner is sequentially applied is determined in advance based on various depth to respective recording layers of a CD, a DVD, and a high-density DVD, and when a disk is placed a servo-control manner is sequentially selected in the determined order. Therefore, a collusion between a disk and an optical pickup can be prevented for any type of disk.

1. TECHNICAL FIELD

The present invention relates to a method for controlling a servooperation of an optical disk apparatus depending upon various kinds ofoptical disks, such as a CD (compact disk), a DVD (digital versatiledisk), and a HD-DVD (high-density digital versatile disk).

2. BACKGROUND ART

As shown in FIG. 1, a general CD is formed with a thickness of 1.2 mmand a diameter of 120 mm. The CD has a center hole of 15 mm in diameter,and a clamped region of 44 mm in diameter and formed around the centerhole. The clamped region is fixed to a turntable of an optical diskapparatus by means of a clamper.

When the CD is properly placed on the optical disk apparatus, arecording layer, on which data are recorded in a pit pattern, is spacedapproximately 1.2 mm from the surface of the CD opposite to an objectlens of an optical pickup of the optical disk apparatus. The object lensof the optical pickup for the CD has a relatively small numeral aperture(NA). For example, the lens has an NA of 0.4-5.

As shown in FIG. 2, a general DVD is formed with a thickness of 1.2 mmand a diameter of 120 mm. The DVD has a center hole of 15 mm indiameter, and a clamped region of 44 mm in diameter and formed aroundthe center hole. The clamped region is fixed to a turntable of anoptical disk apparatus by means of a clamper.

When the DVD is properly placed on the optical disk apparatus, arecording layer, on which data are recorded in a pit pattern, is at adistance of approximately 0.6 mm from the surface of the DVD opposite toan object lens of an optical pickup of the optical disk apparatus. Theobject lens of the optical pickup for the DVD has a relatively largenumeral aperture (NA). For example, the lens has an NA of 0.6.

As shown in FIG. 3, a newly commercialized HD-DVD is formed with athickness of 1.2 mm and a diameter of 120 mm. The HD-DVD has a centerhole of 15 mm in diameter, and a clamped region of 44 mm in diameterformed around the center hole. The clamped region is fixed to aturntable of an optical disk apparatus by means of a clamper. When theHD-DVD U is properly placed on the optical disk apparatus, a recordinglayer, on which data are recorded in a pit pattern, is spacedapproximately 0.1 mm from the surface of the HD-DVD opposite to anobject lens of an optical pickup of the optical disk apparatus.

The object lens of the optical pickup for the HD-DVD has the largestnumeral aperture (NA). For example, the lens has an NA of 0.85. Theoptical pickup for the HD-DVD uses a laser beam having a shortwavelength to reproduce data recorded in high density or record data inhigh density, as compared to the optical pickup for the CD or the DVD.

The object lens of the optical pickup for the HD-DVD is closer to therecording layer of the HD-DVD than that for the CD or the DVD.Furthermore, the object lens of the optical pickup for the HD-DVD hasthe largest numeral aperture, and the optical pickup for the HD-DVD usesthe laser beam having a shorter wavelength than that for the CD or theDVD. Consequently, an increased amount of light can be focused on therecording layer formed in the pit pattern using a small beam spot, andthe light transmittance distance of the laser beam having the shortwavelength can be shortened.

When a HD-DVD 10 is properly placed on a turntable 11 of the opticaldisk apparatus, as shown in FIG. 4, the HD-DVD 10 is rotated at highspeed by a servo operation of a spindle motor 12, a motor driving unit13, and a servo controller 15. While the HD-DVD 10 is rotated, theobject lens OL of an optical pickup 14 of the optical disk apparatusfocus on the HD-DVD 10 on the basis of a focusing servo operation bywhich the object lens OL of the optical pickup 14 is vertically movedwithin the range of an operating distance OD so that reading highdensity data recorded in the pit pattern or recording high density datain the pit pattern is normally carried out.

When the HD-DVD 10 is placed upside down on the turntable 11 of theoptical disk apparatus, or one of other different kinds of optical disksis placed on the turntable 11 of the optical disk apparatus, forexample, when a general CD 20 is placed on the turntable 11 of theoptical disk apparatus, as shown in FIG. 5, the CD 20 is also rotated athigh speed by a servo operation of the spindle motor 12, the motordriving unit 13, and the servo controller 15. In this case, therecording layer of the CD placed on the turntable 11 of the optical diskapparatus is at a distance of 1.1 mm more from the surface of the CDopposite to the object lens OL of the optical pickup 14 of the opticaldisk apparatus, as compared to the recording layer of the HD-DVD.

Under the aforesaid condition, the object lens OL of the optical pickup14 of the optical disk apparatus cannot focus on the CD 20 by a normalfocusing operation for moving vertically the object lens OL. For thisreason, the object lens OL of the optical pickup 14 of the optical diskapparatus is upwardly moved toward the recording layer of the CD 20until it moves the maximum operating distance OD_Max under the controlof the servo controller 15 for controlling the focusing operation.Consequently, the object lens OL of the optical pickup 14 of the opticaldisk apparatus comes into collision with the CD 20, which may cause theCD 20 or the object lens OL of the optical pickup 14 to be damaged, orotherwise cause the servo operation to have fatal errors.

3. DISCLOSURE OF INVENTION

Therefore, the present invention has been made in view of the aboveproblems, and it is an object of the present invention to provide aservo-controlling method of an optical disk apparatus that is capable ofpredetermining the order of servo operations of the optical diskapparatus based on various kinds of optical disks, such as a CD, a DVD,and a HD-DVD, which have different light transmittance depths from thesurfaces of the optical disks opposite to an object lens of an opticalpickup of the optical disk apparatus when each of the optical disks isplaced on a turntable of the optical disk apparatus to recording layersof the optical disks, and sequentially performing the servo operationsaccording to the predetermined order.

In accordance with the present invention, the above and other objectscan be accomplished by the provision of a servo-controlling method of anoptical disk apparatus, comprising: a first step of determining theorder of focusing servo operations of the optical disk apparatus basedon various kinds of optical disks having different light transmittancedepths from the surfaces of the optical disks each opposite to an objectlens of an optical pickup of the optical disk apparatus when each of theoptical disks is placed on a turntable of the optical disk apparatus torecording layers of the optical disks; a second step of sequentiallyperforming the focusing servo operations on the optical disk properlyplaced in the optical disk apparatus according to the predeterminedorder; and a third step of performing a corresponding tracking servooperation on the optical disk when a normal focusing is achieved on theoptical disk in the course of performing the sequential focusing servooperations.

In the servo-controlling method with the above-stated characteristicsaccording to the present invention, collision between the optical diskand the optical pickup of the optical disk apparatus is prevented, andthus the optical disk or the optical disk apparatus is not damaged.Furthermore, fatal errors in the servo operations are effectivelyprevented.

4. BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the structure of a general CD;

FIG. 2 shows the structure of a general DVD;

FIG. 3 shows the structure of a general HD-DVD;

FIG. 4 shows a general HD-DVD properly placed in an optical diskapparatus;

FIG. 5 shows a general CD properly placed in an optical disk apparatus;and

FIG. 6 is a flow chart showing several steps of controlling servooperations of an optical disk apparatus according to the presentinvention.

5. MODES FOR CARRYING OUT THE INVENTION

Now, a servo-controlling method of an optical disk apparatus accordingto a preferred embodiment of the present invention will be described indetail with reference to the accompanying drawings.

As previously mentioned with reference to FIGS. 4 and 5, the opticaldisk apparatus, to which the servo-controlling method of the presentinvention is applied, basically comprises the turntable 11 on which theoptical disk is placed, the spindle motor 12 for rotating the opticaldisk placed on the turntable 11 at high speed, the motor driving unit 13for driving the spindle motor 12, the optical pickup 14 for readingsignals recorded on the optical disk or recording signals on the opticaldisk, and the servo controller 15 for controlling the focusing servooperation of moving the object lens OL of the optical pickup 14vertically relative to the recording layer of the optical disk and thetracking servo operation of moving the object lens OL of the opticalpickup 14 horizontally along the recording layer of the optical disk.

The servo controller 15 predetermines the order of focusing servooperations of the optical disk apparatus based on various kinds ofoptical disks having different light transmittance depths from thesurfaces of the optical disks opposite to the object lens of the opticalpickup of the optical disk apparatus when each of the optical disks isplaced on the turntable of the optical disk apparatus to recordinglayers of the optical disks, for example, the CD having a lighttransmission depth of 1.2 mm, the DVD having a light transmission depthof 0.6 mm, and the HD-DVD having a light transmission depth of 0.1 mm,as previously mentioned with reference to FIGS. 1 to 3. In thisembodiment, the order of the focusing servo operations of the opticaldisk apparatus is determined in such a manner that a first focusingservo operation is performed on the CD, a second focusing servooperation is performed on the DVD, and a third focusing servo operationis performed on the HD-DVD.

Accordingly, when one of various kinds of the optical disks is properlyplaced in the optical disk apparatus, the corresponding focusing servooperation is sequentially performed in the order of the CD, the DVD, andthe HD-DVD until the normal focusing is achieved on the optical diskplaced in the optical disk apparatus.

In case that the normal focusing is achieved on the optical disk, thecorresponding tracking servo operation is subsequently carried out toread data recorded on the optical disk or record data on the opticaldisk, which will be described hereinafter in detail.

FIG. 6 is a flow chart showing several steps of controlling servooperations of an optical disk apparatus according to the presentinvention.

When one of various kinds of the optical disks is properly placed on theturntable 11 of the optical disk apparatus (S10), the servo controller15 controls the motor driving unit 13 so that the optical disk isrotated at high speed by the spindle motor 12.

The servo controller 15 also controls the focusing servo operation ofmoving the object lens OL of the optical pickup 14 vertically relativeto the recording layer of the optical disk. At this time, the CDfocusing servo operation is firstly performed according to the order offocusing servo operations of the optical disk apparatus based on variouskinds of the optical disks having different light transmittance depthsfrom the surfaces of the optical disks opposite to the object lens ofthe optical pickup of the optical disk apparatus when each of theoptical disks is placed on the turntable of the optical disk apparatusto recording layers of the optical disks (S11).

Consequently, the object lens OL of the optical pickup of the opticaldisk apparatus is upwardly moved until it reaches the maximum movableposition predetermined for the CD having the light transmittance depthof 1.2 mm.

When the CD focusing is achieved in the course of upward movement of theobject lens OL of the optical pickup (S12), the tracking servo operationof moving the object lens OL of the optical-pickup 14 horizontally alongthe recording layer of the CD is subsequently performed under thecontrol of the servo controller 15 (S13).

When the central part of the track formed on the recording layer of theoptical disk is normally tracked by means of the tracking servooperation for the CD, i.e., when the normal tracking is achieved (S14),the current CD focusing and tracking servo operations are continuouslyperformed under the control of the servo controller 15. Consequently, aRF signal outputted from the optical pickup is transmitted to a digitalsignal processing unit (not shown) of the optical disk apparatus wherethe signal is processed in a suitable manner (S15).

When the CD focusing is not achieved in the course of upward movement ofthe object lens OL of the optical pickup (S12), the DVD focusing servooperation is secondly performed-according to the order of focusing servooperations of the optical disk apparatus based on various kinds of theoptical disks having different light transmittance depths from thesurfaces of the optical disks each opposite to the object lens of theoptical pickup of the optical disk apparatus when each of the opticaldisks is placed on the turntable of the optical disk apparatus torecording layers of the optical disks (S21).

Consequently, the object lens OL of the optical pickup of the opticaldisk apparatus is upwardly moved until it reaches the maximum movableposition predetermined for the DVD having the light transmittance depthof 0.6 mm.

When the DVD focusing is achieved in the course of upward movement ofthe object lens OL of the optical pickup (S22), the tracking servooperation of moving the object lens OL of the optical pickup 14horizontally along the recording layer of the DVD is subsequentlyperformed under the control of the servo controller 15 (S23).

When the central part of the track formed on the recording layer of theoptical disk is normally tracked by means of the tracking servooperation for the DVD, i.e., when the normal tracking is achieved (S24),the current DVD focusing and tracking servo operations are continuouslyperformed under the control of the servo controller 15. Consequently, aRF signal outputted from the optical pickup is transmitted to thedigital signal processing unit of the optical disk apparatus where thesignal is processed (S15).

When the DVD focusing is not achieved in the course of upward moving ofthe object lens OL of the optical pickup (S22), the HD-DVD focusingservo operation is thirdly performed according to the order of focusingservo operations of the optical disk apparatus based on various kinds ofthe optical disks having different light transmittance depths from thesurfaces of the optical disks opposite to the object lens of the opticalpickup of the optical disk apparatus when each of the optical disks isplaced on the turntable of the optical disk apparatus to recordinglayers of the optical disks (S31).

Consequently, the object lens OL of the optical pickup of the opticaldisk apparatus is upwardly moved until it reaches the maximum movableposition predetermined for the HD-DVD having the light transmittancedepth of 0.1 mm.

When the HD-DVD focusing is achieved in the course of upward moving ofthe object lens OL of the optical-pickup (S32), the tracking servooperation o'f moving the object lens OL of the optical pickup 14horizontally along the recording layer of the HD-DVD is subsequentlyperformed under the control of the servo controller 15 (S33).

When the central part of the track formed on the recording layer of theoptical disk is normally tracked by means of the tracking servooperation for the HD-DVD, i.e., when the normal tracking is achieved(S34), the current. HD-DVD focusing and tracking servo operations arecontinuously performed under the control of the servo controller 15.Consequently, a RF signal outputted from the optical pickup istransmitted to the digital signal processing unit of the optical diskapparatus where the signal is processed (S15).

The aforesaid optical pickup of the optical disk apparatus may comprisea plurality of lasers corresponding to kinds of the optical disks, and aplurality of object lenses having different numeric apertures so thatnormal focusing and tracking servo operations can be smoothly achievedon various kinds of the optical disks, such as the CD, the DVD, and theHD-DVD, which have different light transmittance depths from thesurfaces of the optical disks each opposite to the object lens of theoptical pickup of the optical disk apparatus when each of the opticaldisks is placed on the turntable of the optical disk apparatus torecording layers of the optical disks.

The preferred embodiment of the present invention has been disclosed forillustrative purposes. Therefore, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims. For example, aservo-controlling method of an optical disk apparatus according to thepresent invention may be carried out by means of another component forcontrolling a servo controller, such as a microcomputer for controllingall of the optical disk apparatus.

1. A servo-controlling method of an optical disk apparatus, comprising:a first step of determining the order of focusing servo operations ofthe optical disk apparatus based on various kinds of optical diskshaving different light transmittance depths from the surfaces of theoptical disks opposite to an object lens of an optical pickup of theoptical disk apparatus when each of the optical disks is placed on aturntable of the optical disk apparatus to recording layers of theoptical disks; a second step of sequentially performing the focusingservo operations on the optical disk properly placed in the optical diskapparatus according to the predetermined order; and a third step ofperforming a corresponding tracking servo operation on the optical diskwhen a normal focusing is achieved on the optical disk in the course ofperforming the sequential focusing servo operations.
 2. The method asset forth in claim 1, wherein the first step determines the order of thefocusing servo operations of the optical disk apparatus so that thefocusing servo operations are sequentially performed from the opticaldisk having large light transmittance depth to the optical disk havingsmall light-transmittance depth.
 3. The method as set forth in claim 1,wherein the first step determines the order of the focusing servooperations of the optical disk apparatus so that the focusing servooperations are sequentially performed on the optical disk in the orderof a CD, a DVD, and a HD-DVD.
 4. The method as set forth in claim 3,wherein the second step sequentially performs the focusing servooperations on the optical disk properly placed in the optical diskapparatus in the order of the CD, the DVD, and the HD-DVD.
 5. The methodas set forth in claim 4, wherein the third step performs thecorresponding CD tracking servo operation when the normal focusing isachieved on the CD in the course of performing the sequential focusingservo operations.
 6. The method as set forth in claim 5, wherein thethird step performs the focusing servo operation on the DVD when thenormal focusing is not achieved on the CD, and then performs thecorresponding DVD tracking servo operation when the normal focusing isachieved on the DVD.
 7. The method as set forth in claim 6, wherein thethird step performs the focusing servo operation on the HD-DVD when thenormal focusing is not achieved on the DVD, and then performs thecorresponding HD-DVD tracking servo operation when the normal focusingis achieved on the HD-DVD.